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Neuroscience > Ch. 3: Synapses and Synaptic Transmission > Flashcards

Ch. 3: Synapses and Synaptic Transmission Flashcards

1
Q

What are the 4 parts in the structure of a synapse?

A
  • Presynaptic terminal (axon)
  • Neurotransmitter (crosses space)
  • Postsynaptic Terminal (dendrite or cell body)
  • Synaptic Cleft (space between neurons)
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2
Q

What are the sequence of events at the synapse?

A
  1. Action potential @ presynaptic cell
  2. Depolarize = open voltage-gated Ca++ channels
  3. Ca++ influx move toward release site
  4. Vesicles bind w/ membrane → release neurotransmitters
  5. Neurotransmiters diffuse → move down concentration gradient & spill into synaptic cleft
  6. Neurotransmiters binds receptors → ligand binds with ligand gated channel
  7. Receptor binding initiated changes at post-synaptic membrance
    • Directly opens an ion channel
    • Activates intracellular messengers
  8. Clear synapse/re-set for next action potential
    • enzymes: eat neurotransmitters
    • Reuptake transporters: carry neurotransmitters back into membrane
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3
Q

What type of synapse is A?

A

Axosomatic

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4
Q

What type of synapse is B?

A

Axodendritic

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5
Q

What type of synapse is C?

A

Axoaxonic

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6
Q

How does an Excitatiry PostSynaptic Potential (EPSP) work?

A

Depolarize: Na+ or Ca++ into cell through open channel

“facilitation” → leads toward AP

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7
Q

How does an Inhibitory PostSynaptic Potential (IPSP) work?

A

Hyperpolarize: Cl- into cell or K+ out of cell

“inhibition” → makes difference bigger

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8
Q

What is a presynaptic conneciton?

What type of synape is it (usually)?

A
  • Presynapse of interest before important connection
  • Axoaxonic
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9
Q

What is presynaptic facilitaiton?

A
  • Promotes MORE neurotransmitter - makes signal stronger
    • AP more likely
    • more Ca++ influx = more neurotransmitter release
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10
Q

What is presynaptic inhibition?

A
  • DECREASE neurotransmitter
    • AP LESS likely
    • LESS Ca++ influx = LESS neurotransmitter release
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11
Q

What is the mechanism behind “rub it where it hurts?”

A

Light touch receptors trigger presynaptic inibition → send less pain signals to brain

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12
Q

Where do synaptic membranes fuse with cell membrane?

A

Presynaptic

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13
Q

What are the difference between Neurotransmitters and Neuromdulators?

A
  • Neurotransmitters: ligands released in synaptic cell that bind to ligand gated channels (2 types)
      1. Directly open gates: open & close quick
      1. Indirectly open gate: open & close slow
  • Neuromodulators
    • Nothing directly - effect activity of cell as a whole
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14
Q

What is a “fast acting” neurotransmitter (ligand)?

A
  • Direct activation of ion channel - ligand functioning as neurotransmitter
    • quick open & close
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15
Q

What is a “slow acting” neurotransmitter (ligand)?

A
  • Indirect activation - G-protein mediated receptors linked to ion channel
    • Slow open & close
    • Use G-Protein receptors & G-Protein shuttle system
      • “second messenger system”
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16
Q

What is a neruomodulator?

(aka Cascade of intracellular events or

“second messenger” system)

A
  • Does not directly open anything
    • Released outside synaptic cleft
    • Alter neural function by acting a distance away
    • Response is slower to develop and longer lasting than neurotransmitter
  • ​Ligand is first messenger and starts the process
  • Modulates Ca+ concentrations inside the cell
17
Q

Can a ligand serve as both a neurotransmitter and neuromodulator?

A

Yes.

Depending on whether released into synaptic cleft or into extracellular fluid

One nerve terminal may release multiple ligands

18
Q

What is the excitatory neurotransmitter of the PNS?

A

Acetylcholine

19
Q

What is the excitatory neurotransmitter of the CNS?

20
Q

What is the inhibitory neurotransmitter of the PNS?

A

There is not one!

21
Q

What is the inhibitory neurotransmitter of the CNS?

22
Q

What is “Up” regulation?

A
  • Either Inserted or activated
    • Become more numerous
23
Q

What is “Down” regulation?

A
  • Either remove or inactivate
24
Q

What is an agonist action?

A

Produces the same effect as neurotransmitter

25
Q

What is an antagonist action?

A
  • Prevents ligand from being released
  • Signal to move muscle is still coming but this prevents neurotransmitter from being released (Ex: Botox)
26
Q

What is effected in patients with Myasthenia Gravis?

A
  • Problem of synaptic transmission
  • Decreased binding of ACh at postsynaptic membrane → muscle contraction can be formed but not sustained
27
Q

What is effected in patients with Depression?

A
  • Post synaptic membrane does not accept Serotonin well
  • SSRI: Selective Serotonin Reuptake Inhibtor
    • Enhances activity of serotonin by keeping it in synaptic cleft

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